Operating point selection for dendritic growth during rapid solidification

A phase-field model of non-isothermal solidification in binary alloys has been used to study the variation of growth velocity, dendrite tip radius and radius selection parameter, σ*, as a function various process and materials parameters. We find that σ* is non-constant and, over a wide parameter space, displays first a local minimum followed by a local maximum as the undercooling is increased. This behaviour is contrasted with a similar type of behaviour to that predicted by simple marginal stability models to occur in the radius of curvature for constant σ*.